<span>Start at descendant:</span>
<mat-button-toggle-group (change)="handleChange()" [(ngModel)]="selection">
  <mat-button-toggle value="reference">A1</mat-button-toggle>
  <mat-button-toggle value="id">A2</mat-button-toggle>
  <mat-button-toggle value="custom">A3</mat-button-toggle>
</mat-button-toggle-group>
<td-markdown-navigator
  [items]="items"
  [startAt]="startAt"
  [compareWith]="compareWith"
  [style.height.px]="200"
></td-markdown-navigator>
